The present invention relates to a compression recovery sheet which is lightweight, bulky and thin and has high compression recovery properties, a process for producing the same, and an absorbent article containing the same. More particularly, the present invention relates to a compression recovery sheet such as may be used as a constituent member to provide an absorbent article, etc., such as a disposable diaper and a sanitary napkin, that is thin in a packaged state (under some load) but recovers thickness on being taken out of the package (on removal of the load) to gain a sufficient thickness required of the absorbent article, etc. enough to give users a feeling of assurance, a process for producing the same, and an absorbent article containing the same.
The recent absorbent articles such as disposable diapers and sanitary napkins have been made more compact and easier to carry in packages by improvements added to the structure and the material. However, if absorbent articles such as disposable diapers are made thinner to make the package more compact, the absorbent article lacks stiffness and makes a user feel a fear of leakage during use. Therefore, it has been demanded to develop absorbent articles which are compact and light in their packaged state but restore their thickness when taken out of the package for use thereby giving a user a feeling of assurance while worn.
In order to eliminate the fear of leaks during use, it has been proposed to use a fiber aggregate, such as nonwoven fabric made of polyester fiber or thermally fusible fiber or a mixed sheet of these fibers and pulp as a cushioning layer in absorbent articles. Such fiber aggregates include those described in Japanese Patent Laid-Open Publication Nos. 61-106151 and 1-285265. For example, the Publication No. 1-285265 discloses an absorbent article having an elastic member of a fiber aggregate mainly comprising synthetic fiber under an absorbent member. The subject matter of the invention disclosed resides in disposing nonwoven fabric formed of synthetic fiber having high elasticity under an absorbent member to absorb the stress imposed on the absorbent member and to secure recovery properties thereby to prevent leakage. However, the fiber aggregates according to these publications fail to perform the function as a cushioning layer of an absorbent article in actual use or after relief from a highly compressed state, for example, a packaged state.
Use of a fiber aggregate comprising an elastomeric component as a cushioning material has also been proposed in the fields other than absorbent articles, such as furniture, beds, seats, and the like (see Japanese Patent Laid-Open Publication Nos. 5-161525 and 7-316963). However, the fiber aggregates proposed as a cushioning material have, in nature of the purpose of use, a very large basis weight and a large thickness not smaller than 5 mm, practically 50 mm or greater. For these reasons and for the economical consideration, they are inapplicable to absorbent articles. Although urethane foam could be a conceivable cushioning material of an absorbent article, it is unacceptable because of not only high cost incurred but yellowing and smell.
An object of the present invention is to provide a compression recovery sheet which is thin in a packaged state (under some load) but restores thickness on being taken out of the package (on removal of the load) to gain a sufficient thickness required of an absorbent article, etc. enough to make a user feel assured, a process for producing the same, and an absorbent article containing the same.
Another object of the present invention is to provide a compression recovery sheet which is suited for use as a cushioning material of furniture, beds, seats, and the like.
The present invention provides a compression recovery sheet which comprises a fiber aggregate containing 10 to 90% by weight of an elastomeric component and has a basis weight of 15 to 100 g/m2, a no-load thickness of 1 to 10 mm, and a compressive recovery of 60% or more.
The present invention also provides a compression recovery sheet which comprises a fiber aggregate substantially comprising synthetic fiber and having been impregnated or coated with an adhesive whose glass transition temperature is 4xc2x0 C. or lower and has a basis weight of 15 to 100 g/m2, a no-load thickness of 1 to 10 mm, and a compressive recovery of 60% or more.
The present invention further provides a preferred process for producing the above-described compression recovery sheet, which comprises heat treating a fiber aggregate web to form a fiber aggregate sheet and heat rolling the sheet with an engraved roll.
The present invention furthermore provides an absorbent article comprising a liquid permeable topsheet, a liquid-impermeable leakproof sheet, a liquid retentive absorbent member interposed between the topsheet and the leakproof sheet and, as a cushioning member, the above-described compression recovery sheet.